1. Field of the Invention
The present invention relates generally to multilayer circuit boards, and more particularly to multilayer circuit boards having air bridge circuits.
2. Disclosure Information
In the printed circuit board (PCB) industry, various methods are used to produce multilayer (i.e., two-or-more-layer) PCBs. U.S. Pat. No. 4,404,059 to Livshits et al. (hereinafter "Livshits") and Pat. Ser. No. 5,738,797 to Belke et al. (hereinafter "Belke"), both of which are incorporated herein by reference, describe "additive" processes for PCB construction, while U.S. Pat. No. 3,801,388 to Akiyama et al. (hereinafter "Akiyama"), also incorporated herein by reference, teaches a "subtractive" process for PCB manufacture. These additive and subtractive processes involve various masking, plating, mask-stripping, chemical etching, and other steps for constructing multilayer circuit boards having features known as "air bridges", "crossovers", "air bridge crossovers", and the like.
Air bridge crossover circuits are useful for creating high density circuits. However, such circuits sometimes suffer from susceptibility to mechanical damage, caused by physical impact, thermal excursions, and the like. It would be desirable, therefore, to provide a way of creating such multilayer air bridge circuits without this drawback.